A window watchdog provides timing supervision for processing circuits (processors), such as CPUs (Central Processor Units), DSPs (Digital Signal Processors), microcontrollers, or other processor based systems. A conventional window watchdog is configured to receive a trigger information from the signal processing circuit and is configured to detect whether the trigger information has been received within a first time window, known as closed window, or within a second time window, known as open window. The watchdog may reset the signal processing circuit when the trigger information has been received in the closed window.
In a conventional watchdog, the open and closed windows are generated in the watchdog based on timing information stored in the watchdog, so that the timing information is fixed once it has been programmed into the watchdog.
There is a need to provide a supervisory circuit with a window watchdog that can be easily synchronized to the supervised processing unit in the normal operation of the window watchdog.